K_v2.1 clusters on β-cell plasma membrane act as reservoirs that replenish pools of newcomer insulin granule through their interaction with syntaxin-3.

ABSTRACT: The voltage-dependent K⁺ (K_v) channel K_v2.1 is a major delayed rectifier in many secretory cells, including pancreatic β cells. In addition, K_v2.1 has a direct role in exocytosis at an undefined step, involving SNARE proteins, that is independent of its ion-conducting pore function. Here, we elucidated the precise step in exocytosis. We previously reported that syntaxin-3 (Syn-3) is the key syntaxin that mediates exocytosis of newcomer secretory granules that spend minimal residence time on the plasma membrane before fusion. Using high-resolution total internal reflection fluorescence microscopy, we now show that K_v2.1 forms reservoir clusters on the β-cell plasma membrane and binds Syn-3 via its C-terminal C1b domain, which recruits n

SUBMITTER: Greitzer-Antes D 

PROVIDER: S-EPMC5936832 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature